Designers of electronic circuits must incorporate into their designs methods to control heat generated by electronic components in the circuit. Unless controlled, the heat build-up will cause component and circuit failure. Temperature control, therefore, is vital to circuit reliability. The preferred method to controlling temperature is to dissipate the excess heat into the ambient air surrounding the electronic circuit before temperatures rise to a level where damage can occur.
The traditional method to contain temperature build-up is to associate heat generating components with heat dissipation devices, such as heat sinks. The heat dissipation device absorbs heat from the component and provides for a more efficient transfer of excess heat into the surrounding ambient air. In most cases, the heat generating component will be mounted directly to the heat dissipation device to more efficiently remove the excess heat.
Although traditional heat sinking methods can be used successfully in most cases, the problems associated with temperature control have become more pronounced as electronic circuits have become more complex. Such circuit complexity often results in a circuit that requires a larger number of components, which frequently are more powerful and can generate even more heat. The problem is further complicated by the fact that lower profile and more compact electronic systems have become the preferred choice of customers. This means that space must be found in such low profile, compact systems for both the electronic components that make up the circuit as well as the heat dissipation devices that such components require in order to prevent heat related damage. In short, as the power density of circuits has increased, the use of classic finned heat sinks may no longer adequately address the corresponding heat dissipation requirements.
Some of the foregoing problems have been resolved by using active, rather than passive, systems to control temperature build up. For example, certain board mounted electronic components that generate large amounts of heat can have an active cooling device, such as a small fan, dedicated solely to the device. In those situations where a fan is used as the active device, the fan is typically mounted directly on the component and improves cooling by moving more ambient air over the component. Using a fan in this manner will provide more efficient cooling in less space than a classic finned heat sink.
Notwithstanding the benefits of having an active cooling device associated directly with a heat generating component, active cooling devices have certain shortcomings. One shortcoming is that such a device requires its own power source in order to operate. Prior art methods of providing this power usually involved the provision of a separate wiring path for the active device. Such a path may be provided by using separate connector pins on the substrate that are directly connected to the active device. This solution to the power problem raises additional problems, such as the added manufacturing expense of connecting the active device to an electrical power source during the assembly process. Other detrimental factors may arise when the active device must be removed for replacement or maintenance. Usually the active device must be manually disconnected and, when reinstalled, manually reconnected. This increases maintenance time and the potential for error.
Accordingly, what is needed in the art is a device that can provide electrical power to an active cooling device mounted on an electronic device that does not require a separately wired circuit.